EMCrit Podcast 33 – Diagnosis of Posterior Stroke

What if I told you that I think that patient you just sent home with vertigo may have been a missed cerebellar stroke? Would you be dialing risk management or could you tell me all of the reasons why I’m wrong? Isolated vertigo without other neurological findings can’t be a stroke, right? That is true, if you are doing the right exam, but if you are just doing your standard ED neuro screening exam then you might be missing serious pathology. In this episode of the EMCrit podcast, I discuss how to perform the tests that will differentiate a peripheral cause of continuous vertigo from a cerebellar stroke.

Drs. David Newman-Toker & Jorge Kattah, neurologists at John Hopkins, have done a ton of work on this topic. They have created an mnemonic for the exam you should be doing on all of your patients with continuous vertigo (as opposed to positional, intermittent vertigo, i.e. BPPV). Benign positional paroxysmal vertigo is not ED critical care. Continuous vertigo, also known as acute vestibular syndrome, may be. The mnemonic is HiNTS.

Hi for head impulse testing, or head thrust testing.
N for nystagmus to remind you to look for direction-changing or vertical nystagmus
TS for test of skew.

I will discuss what all of these terms mean and how to perform the exams in the podcast.

Discussion

I was pretty excited about David Newman-Toker’s papers at first, but I’ve become a little skeptical that the HiNTS battery — in particular, the head impulse test — is a magic test for detecting cerebellar stroke in the ED.

First of all, the head impulse test is tricky to perform, and the result you’re looking for is quite subtle. And although all the papers say you can perform the test in the presence of spontaneous nystagmus, a non-expert (like me) has a lot of trouble distinguishing nystagmus from a catch-up saccade when the patient’s eyes are bopping around like crazy.

Second, it’s really impossible to perform the test in someone with severe head-motion intolerance — for example, our acutely dizzy patients early in their course. Diaphoretic, ashen, vomiting, eyes clenched shut and holding their heads perfectly still — there’s no way these patients will tolerate having their heads snapped back and forth, much less open their eyes and fix on a target.

In Newman-Toker’s HIT paper, the average time from symptom onset to exam was about 10 1/2 hours, and many patients were examined days after onset — by which time I bet most of them were pretty comfortable. But that’s not most of our patients. So it’s a great test for the Neurology team upstairs the next morning, or a few days later in clinic, but not so great early on, when we need it most. I think we’re better off looking for red flags — especially headache or neck pain, or unsteadiness out of proportion to spinning. That’ll catch most of our cerebellar strokes.

I think I need to clarify for which patients I believe the HINTS exam is important.
If the patient has any worrisome signs, i.e. the profound ataxia you mention, a headache in association with the vertigo, any hard neurological findings, then no HINTS necessary–pursue MRI and neurological consultation. Or if the patient is elderly (though I don’t have an exact age cut-off for when that designation begins), they probably should be admitted with neurology onboard regardless of the HINTS exam.

But if you have a patient with isolated vertigo with a pristine routine neuro exam, who you were about to send home, then HINTS becomes very valuable. If the HINTS exam is non-reassuring, then that is a potential save.

So I use HINTS as a last fail safe and not as a means to discharge a patient I was concerned about prior to doing the test.

As to performing the Head Impulse, I agree it certainly it can be tough sometimes. However, for me it is the BPPV patients that have the extreme head motion intolerance. Most of the AVS patients (continuous vertigo, with only mild positional component) can tolerate the test.

My experience is a little different — my BPPV patients don’t (and, I think, shouldn’t) have head-motion intolerance in the horizontal plane (for example, the head-impulse test), only in the vertical plane (the Dix-Hallpike). As for the patients with continuous vertigo, many are — as you say — comfortable by the time they come to us. The ones who aren’t are a real challenge for any sort of testing.

In general, I think the difficulty with vertigo comes at the beginning, with the basics. A lot of docs don’t realize, for example, that brief dizzy spells and long, continuous attacks have a completely different differential diagnosis. As a result, they order MRIs for older patients with BPPV to rule out (nonexistent) strokes, and perform the Dix-Hallpike maneuver on patients with continuous vertigo (inevitably the patients feel worse on one side than the other, leading to a spurious diagnosis of BPPV).

Our subspecialty consultants are often just as confused. A few weeks ago a Neurology consult informed me that my patient — an elderly woman with three days of constant vertigo, vomiting and ataxia — “clearly” had BPPV because she had “a positive Epley maneuver to the left.” Sigh.

This comment hits a lot of nails on the head.
Doing HINTS on people with short episodes of vertigo, and Dix-Hallpike on people with with ongoing vertigo and spontaneous nystagmus is a huge problem.

One thing which I have grown to appreciate is that horizontal canal BPPV is not uncommon. In fact I’ve seen 3 in the past few months. These patients may in fact get very vertiginous with simple head turning in the horizontal plane. See my video on my youtube channel on how to diagnose and treat it.

http://www.youtube.com/watch?v=BNP5UiRlmiU
I just posted this video of a HINTS exam with positive head impulse test using an iphone 5S, in 120 FPS mode. The catch up saccade is unmistakable in the slowed down portion of the video. I think this might be the best positive head impulse ON THE INTERNET!

Newman-Toker’s review paper emphasizes the challenge in defining the dizziness type; aka dizziness type is an imprecise metric and ED patients are unreliable historians. So how then does one appropriately identify a patient as having “acute vestibular syndrome” (vertigo, nystagmus, nausea/vomiting, head-motion intolerance, unsteady gait)? Doing so must involve clarifying a patient’s dizziness type, no? In my view, the methodology described in “HINTS to Diagnose Stroke in the Acute Vestibular Syndrome” study lacks clarity. How exactly were the acute vestibular syndrome patients selected? I see Newman-Toker’s view in his review that defining dizziness as being nearly a fruitless effort on one hand and then applying this HINTS exam specifically in patients with the acute vestibular syndrome (which by default involves defining dizziness type) as being contradictory.

Scott,
Quick question.
In some recent shadowing experience I did in the emergency room here in Tennessee. The doctor and I were discussing vertigo and different ways to determine things clinically. He had heard of this “head impulse test” in medical school and had used it a couple of times in residency but has since moved away from it. When I asked about his reasoning he said “Next patient we get in here with vertigo, try that test. They may vomit all over your shoes and scrubs, and I can promise you they are not going to be very happy with the care they received. haha”
What I was asking is have you seen this in your practice and what are you doing to get around it?
Cause it makes sense, I mean if you take a person that is already dizzy and turn their head quickly they are not going to be very happy.

Key is not to try this test on the positional vertigo patients. The folks with continuous vertigo generally won’t vomit on you from moving their head around especially in the horizontal plane. Try the test on a bpv patient and you may need a change of scrubs, but it’s not helpful on these patients anyway.

I just came across this Podcast and was somewhat surprised by it. Why was critical analysis of these tests left out? No mention of sensitivity and specificity and how applicable and helpful these tests would be to the undifferentiated vertiginous patient who presents to the ED?

I can’t imagine attempting to order an MRI or transfer a patient to get one based on a NORMAL head impulse test.

Skew deviation may-be predictive of badness, but I’d be very surprised if this was your only abnormal neurologic symptom, as in you were about to send the patient home, but hold on, their alternate cover test detected vertical ocular misalignment, patient is saved from being discharged with horrible cerebellar stroke. Instead gets admitted where…. no intervention could be done anyway.

It’s like we went to the archive and found Kernig and Brudzinski tests, and are now touting them as being clinically useful.

Unleashing these tests on the average ED practitioner without a thorough understanding of which subset of patients to perform them in, and without an understanding of the limitations of these tests seems unlikely to be helpful and more likely to cause confusion and over testing.

Thanks for writing! Before I respond, let me ask a few questions:
1. Did you listen to the podcast? I am not asking that to be flip; many folks comment just based on the blogpost?
2. Did you read the linked articles discussing the test characteristics?
3. Did you read the comments above?
4. Could you tell us your level of training and type of practice?

Question: as I understand the HiNTS exam, it is to be applied to patients with continuous vertigo/symptoms, not intermittent. However, a consulting neurologist opined the opposite. Could you clarify? Thanks

Scott, I agree with the other comments – I’m not sold on the HINTS exam. The head impulse testing I find is difficult to perform and probably likely to send a lot of “normal” exams to imaging they don’t need in the low risk population we see which doesn’t appear to be the population HINTS was studied in. This post I found makes the argument well in reference to an updated study of HINTS.http://emnerd.com/adventure-veiled-lodger

The population we are talking about need something more, whether it be neuro consultation, MRI, or HINTS. AVS can not be ruled out as badness with a standard neuro exam. I’m not sure what you mean by low risk, I think you may be mixing in other forms of vertigo.

the studies are certainly interesting but I do wonder how well it will be applied by the average ED doc around the world compared to a few select neurologists well experienced in its use. The head impulse testing in particular is a difficult test.

Oh wow, this happened to me as a student in IM, pt admitted for dizziness and I was assigned to him. Someone got the wrong idea this pt came in freq for dizziness but I checked his record and never admitted for anything neuro related. I gave him a full neuro and the cerebellar tests were off but Romberg was positive. But overall because of the he himself said he flet like he was walking like a drunk person when trying to get to the hospital and I agreed when I saw him try to walk it seemed more significant than the romberg being piositive and the Confounder was that 2 days ago he had been discharged from nearby hosp and had a CT and MRI which were all negative. But I my stomach said something was off but I think that ALL the time as a student. So every day I presented what I thought were his significant findings and symptoms to anyone involved or near his door until someone kicked me out or found a way to shut me up. Then 2 days later neuro came back and ordered every lab and head study, there were labs I never knew existed for things I didn’t know you could test with labs. Anyway, didn;t take long, first head study, CT showed the stroke!! I wasn’t crazy..BTW it’s me the student who who got to work with you twice and commuted to philly everyday.

Again, thanks so much for bringing up head impulse test to minds of ED clinicians. I’ve been using this test for quite some time and I still get blank deer-eye looks from other docs when I talk about this test and I’d say most docs still are not aware of this test. The HINTS test and its study from 2009 was ok but I find the CMAJ article too biased with one of the authors blatantly promoting the HINTS test and study throughout the article. It’s a very small study still and the 100% sensitivity touted really shouldn’t be taken literally. There are vast limitations, one of which is that their definition of acute vestibular syndrome had to have >24 hour duration by definition and most, if not all, of our ED patients come to ED with less than 24 hours of symptoms of vertigo/dizziness. Also, some migranous vertigo (with normal HIT) lasts over 24 hours as their review said and, hence, the 100% sensitivity of HINTS test should really not be taken literally.
There is a even better dizziness/vertigo article, called ‘a practical approach to acute vertigo’ from Practice Neurol 2008. This is the article that initially introduced the HIT (head impulse test) to me for evaluation of patients in ED and it’s a far better and more relevant vertigo article for ED docs.
Keep up the awesome work!

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Hi, my name is Scott Weingart. I am an ED
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